From mid-October to late December 2024, our NPT3700 slurry balance shield machine successfully completed shield tunneling for the No.3 Utility Tunnel Project on Ningbo Century Avenue (Xingning Road – Dongming Road Section). Operating stably with high tunneling precision and favorable construction efficiency amid complex urban municipal conditions, the equipment finished full-line tunneling to stringent quality standards. It ensured safe and efficient construction of the utility tunnel along the city’s main artery and fully demonstrated the outstanding comprehensive performance of our medium-and-small-sized slurry balance shield machines.

Urban utility tunnels constitute core municipal infrastructure, which impose extremely strict requirements on construction safety, surface settlement control, tunnel forming quality and project schedule. The shield tunneling section of the No.3 Utility Tunnel on Ningbo Century Avenue extends 400 meters in total. The tunnel crown is buried at a depth of approximately 15 to 16 meters, and the alignment features a minimum turning radius of merely 250 meters. Located alongside an urban major road, the project is surrounded by dense buildings and pipelines within a sensitive construction environment. Tunneling along small-radius curves is prone to attitude deviation, geometric defects and stratum disturbance, setting demanding standards for the shield machine’s attitude adjustment accuracy, tunneling stability and working condition adaptability.

The NPT3700 slurry balance shield machine deployed for this project is specially optimized for deep-buried, small-curve and sensitive-stratum conditions of urban utility tunnels, making it suitable for urban tunnels with medium and small cross-sections. Equipped with a high-precision slurry balance control system, the machine dynamically adjusts slurry pressure and tunneling parameters in real time to stabilize the excavation face and accurately control stratum settlement, minimizing construction impacts on adjacent roads, pipelines and structures. Furthermore, it delivers excellent performance for curved tunneling, enabling smooth excavation along the 250-meter small-radius curve. The tunnel alignment remains regular and tunneling attitude stays controllable throughout construction, fully meeting all technical specifications of the project.

The project maintained a tight and efficient construction schedule. Shield tunneling officially started in mid-October 2024. During construction, the NPT3700 slurry balance shield machine operated smoothly with a low failure rate. The construction team scientifically optimized tunneling technologies, rationally managed construction milestones and advanced each tunneling phase steadily. Shield receiving was successfully accomplished by late December 2024, marking the full completion of all tunneling works. Remarkable results were achieved on site; the equipment demonstrated prominent high-efficiency tunneling advantages and attained an excellent maximum daily advance of 20 meters, equivalent to 25 rings per day. The project satisfied all targets covering construction quality, operational safety and progress control.

The successful completion of the utility tunnel project on Ningbo Century Avenue once again verifies the strong adaptability and reliable working performance of the NPT3700 slurry balance shield machine for urban utility tunnels and deep-buried small-curve tunnel construction. This project provides an efficient and reliable equipment solution for underground utility tunnel development in Ningbo. It also accumulates mature construction experience for similar municipal tunnel projects with sensitive surroundings and small-radius curves in urban core areas, continuously facilitating the high-quality development of urban underground infrastructure.